Hereinafter, a conventional strain detector is described.
A conventional strain detector includes a plate-like strain generator formed with a plurality of through holes, a resistor element arranged between the through holes of this strain generator and a signal processing circuit connected with the resistor element. A resistance of this resistor element varies depending on the amount of strain.
The load of a passenger sitting on a vehicle seat can be measured, for example, by mounting this strain detector between the vehicle seat and a floor surface portion. Specifically, the strain detector can be mounted by inserting a part of the vehicle seat into the inner one of the plurality of through holes formed in the strain generator to connect the strain generator and the vehicle seat, and inserting a part of the floor surface portion into the outer through hole to connect the strain generator and the floor surface portion. If the parts of the vehicle seat and the floor surface portion mentioned here are, for example, screw portions and are tightly fastened by nuts via the strain generator, the vehicle seat and the floor surface portion are connected. When a load acts on the vehicle seat, the resistance of the resistor element varies if the strain generator is strained. The load can be measured by processing this resistance variation in the signal processing circuit. In this case, since the strain generator is connected with both the vehicle seat and the floor surface portion, a load in a compression direction and a load in a tensile direction can be measured.
Some of such strain generators have cylindrical shapes besides plate-like shapes. Any of these is designed to mount a strain detector by combining a plurality of mounting parts.
Patent literatures 1, 2 are, for example, given as prior art literature information relating to the invention of this application.
Patent Literature 1:
Japanese Unexamined Patent Publication No. 2003-240633
Patent Literature 2:
Japanese Unexamined Patent Publication No. H06-207865
The above conventional strain detector requires a plurality of mounting parts in order to be mounted. Thus, the conventional strain detector had problems of poor assembling efficiency and poor usability.